Spray nozzle

ABSTRACT

A spray nozzle the body of which is provided with a circumferential spray orifice. The orifice is defined by faces on two pieces which are adjustable relatively to one another so that the width of the orifice can be varied. The body is formed by rotating an aerofoil section about a chord of the section and the orifice is positioned so that spray fluid is directed in a dishformation towards the end of the body which, in aerial spraying, is the leading end. If the nozzle is used in a stationary condition, then an airstream is caused to flow over the body from said leading end. A one-way valve is provided which is adapted to be opened by the pressure of the spray liquid fed to the nozzle.

United States Patent [72] inventors Johannes Hendrik Rautenbach NatalProvince; Maitland Reed, Westville, Natal, both of South Africa [21]Appl. No. 820,544 [22] Filed Apr. 30, 1969 [45] Patented Nov. 9, 1971[73] Assignee Aviation Design & Engineering Company South Africa [32}Priority May 8, 1968 1 33] South Africa [31] 68/2980 [54] SPRAY NOZZLE 4Claims, 3 Drawing Figs.

[52] US. Cl 239/11, 239/171, 239/456, 239/581 [51] int. Cl B05b 1/06[50] Field of Search 239/1 1, 171, 456, 457, 451, 569, 570, 571, 581,582; 244/137; 134/166 C; 60/3974 S 56] References Cited UNITED STATESPATENTS 1,982,590 l/1934 Church et al. 134/167 X Primary Examiner-M.Henson Wood, Jr, Assistant Examiner-Michael 1. Mar Atwrney Karl W.Flocks ABSTRACT: A spray nozzle the body of which is provided with acircumferential spray orifice. The orifice is defined by faces on twopieces which are adjustable relatively to one another so that the widthof the orifice can be varied. The body is formed by rotating an aerofoilsection about a chord of the section and the orifice is positioned sothat spray fluid is directed in a dish-formation towards the end of thebody which, in aerial spraying, is the leading end. If the nozzle isused in a stationary condition, then an airstream is caused to flow overthe body from said leading end. A one-way valve is provided which isadapted to be opened by the pressure of the spray liquid fed to thenozzle.

SPRAY NOZZLE BACKGROUND TO INVENTION This invention relates to sprayingand to nozzles for use in spraying.

A requirement for the efficient spraying of liquid dispersoids from anaircraft in flight is that the liquid particles should be relativelysmall, constant in size and uniformly spaced throughout the swath area.Then the number of particles of a selected size per unit area depositedupon the surface will be principally a function of the volumetric flowrate of liquid from the noule. This flow rate may vary from 2 to 4ounces per acre with the ultra-low-volume technique to ten gallons ormore per acre with the high volume system of crop spraying.

Spray noales presently in use for aerial spraying purposes have had onlya limited measure of success. Moreover, they present problems inadjustment and in cleaning and tend to clog when discharging solutionsof wettable powder. In general these nozzles have been adapted fromnonles used for spraying liquid into still air and when used in ahigh-speed airstream their eflect is inhibited because there is atendency for some of the fine liquid particles to agglomerate intolarger liquid particles. This can be undesirable for the largerparticles of the chemical fluids being sprayed may damage the crops.

A further disadvantage of the types of spray nozzle which are in generaluse is that they have high drag characteristics which impair the speedand performance of the aircraft to which the nozzles are attached. Someknown nozzles use rotating parts which require regular maintenance.

A primary object of the present invention is to provide an improved formof spray nozzle which is specifically designed for use in a rapidlymoving airstream. Specifically; the nozzle has been designed for theaerial crop spraying of agricultural insecticides, fungicides andfertilizers in the form of a liquid concentrate, solution or dispersion.The nozzle is suitable for other duties involving the dispersion ofliquids in airflows such as in open circuit cooling towers, in spraypainting, for the spraying of detergents over oil slick at sea andsimilar operations. Another important application envisaged is the useof the nozzle as a liquid fuel atomizer in gas turbine engines.

SUMMARY OF THE INVENTION According to the invention, there is provided anozzle having a body formed with a circumferential spray orifice.

The body may be elongated and the spray orifice may be situated roughlyabout midway along the length of the body between its front and rearends. If desired, the body may be a solid of revolution and obtained byrevolving an aerofoil section about a chord of the section. The aerofoilsection may conveniently be that known as NACA 65 -021 section. Themaximum cross-sectional diameter of the body is about onefifth itslength, and occurs about halfway along the length of the body.

The circumferential spray orifice may conveniently be located at theposition of maximum diameter of the body. The nozzle body may includetwo pieces with the spray orifice defined between axially spaced,circumferential faces. The orifice may communicate with a cavity adaptedto receive spray fluid under pressure. The faces may conveniently befrustoconical, and may be disposed at an inclination to the axis of thenozzle. The faces conveniently diverge forwardly towards the front endof the nozzle. The inclined angle between the axis and the faces may beof the order of 60. The axial width of the spray orifice mayconveniently be adjustable by having the piece on which one of the facesis formed mating screw-fashion with a further piece.

The nozzle may conveniently be provided with an inlet connectioncommunicating with the cavity, this inlet connection being providedahead of the spray opening and preferably at a position about one-thirdback from the front of the nozzle. More particularly, the inletconnection can be provided about 32% percent of the body length inwardlyfrom the nose. If desired, a nonreturn valve may be provided in thebody.

Further according to the invention, eludes discharging spray liquid, inthe fonn of a generally dishlike curtain, into an airstrearn. Theairstream may result from the forward motion of the nozzle such asoccurs in aerial spraying. if the nozzle is stationary, as in spraypainting, when used in a cooling tower or when used as a fuel atomizerfor a gas turbine engine, then the airflow must be induced.

Conveniently, the curtain is concave against the direction of flow ofthe airstream, i.e. flow takes place into the dished formation.Preferably, the curtain is frustoconical.

According to another aspect of the invention, a method of sprayingincludes directing a flow of gaseous fluid into a dished formation ofspray liquid, the flow of gaseous fluid striking the concave face of thedished curtain.

The slope of the dished curtain may conveniently be about 60 to thedirection of airflow.

SPECIFIC DESCRIPTION The invention will now be described in more detail,and by way of example, with reference to the accompanying drawings inwhich;

FIG. 1 is an axial section of one form of nozzle in accordance with thepresent invention;

FIG. 2 is a cross section taken along line -11 of FIG. 1; and

FIG. 3 is an axial section of a further form of nozzle in accordancewith the present invention.

Referring firstly to FIGS. 1 and 2, the nozzle is generally indicated bythe reference numeral 10 and the overall shape of the elongated body ofthe nozzle is that obtained by rotating an aerofoil section about achord 12 so that the chord constitutes the axis of the resultant solidof revolution. If the section is the one known as NACA 65,-021 then themaximum cross-sectional diameter of the body is about 21 percent (i.e.approximately one-fifth) of its length and occurs at a distance from theleading edge or nose of the body equal to about 45 percent of the lengthof the body.

The nozzle is made up of a number of different parts including anosepiece 14, a tailpiece 16, a centerpiece l8, and a boss 20. The boss,centerpiece, and nosepiece are secured together by means of screws 22.An inlet connection 24 is provided into the centerpiece 18. v

The boss 20 has a cylindrical portion 26 terminating in a rounded,annular seat 28. A diaphragm 30 is clamped between the centerpiece 18and the nosepiece 14. The diaphragm is urged against the annular seat 28by means of a disc 32 and a spring 34. The diaphragm 30 may bereinforced and may be of neoprene or other suitable material. The spring34, the disc 32, and the diaphragm 30 together form a nonreturn valve.

The boss 20 has a fine male thread on a tail portion 36 which mates witha fine female thread in the tailpiece 16.

A circumferential spray orifice 38 is defined by the longitudinallyspaced, circumferential faces 39 and 40 of the tailpiece l6 and thecenterpiece 18 respectively and is situated in the region of maximumdiameter of the body, that is, in the region midway between the frontand rear ends of the body. It is possible to obtain infiniteadjustability in the width of the circumferential spray orifice 38 bylongitudinally adjusting the faces 39 and 40 with respect to oneanother. This is effected by rotating the tailpiece l6 and the boss 20with respect to one another so that the fine threads convert this motionto longitudinal motion and cause the faces 39 and 40 to move together orapart. Undesirable movement between the tailpiece l6 and the centerpiece18, Le. after manual setting of the orifice gap by calibrated markings,is prevented by a stiff compression spring 42 located between thetailpiece l6 and the boss 20 and serving to urge the flanks of thethreads against one another.

Dowels 44 serve to locate the boss and centerpiece relatively to eachother.

A cavity 45 communicating with the spray orifice 38 is fed from theinlet connection 24 via the annular seat 28 and via radial holes 46leading into the cavity 45. The inlet connection a method of sprayinginis between the front end and the orifice 38 and is approximatelyoneethird of the length of the body away from the front end (32 percentof the length to be precise). It will be noted that the faces 39 and 40are frustoconical and are so positioned that the orifice is directedtowards the front end of the body. The slope of the faces 39, 40defining the spray orifice 38 is about 60 to the axis 12 and the facesdiverge slightly towards said front end. Openings 50 and 52 serve as airbleed passages.

In use, the nozzle body is mounted such that its axis 12 is parallel tothe direction of air flow, shown by arrows 48. In operation, the sprayliquid enters the nonle under pressure through the inlet connection 24.The liquid pressure opens the nonretum valve by deflecting the diaphragm30 which allows the spray liquid to flow through the central stem of theboss 20 and out through the radial holes 46 into the cavity 45communicating with the spray orifice 38. The faces 39 and 40 definingthe spray orifice are so positioned that the spray liquid is ejected ina forwardly inclined sheet in the form of a generally dishlike curtain.The curtain is in this case frustoconical. As the spray liquid leavesthe spray orifice, it strikes the air flowing over the outer surface ofthe nozzle body, and the relative motion between the airflow and thesheet of liquid gives rise to a shearing action which shatters theliquid sheet into particles whose size varies with the annular gapsetting for particular conditions of liquid pressure, liquid properties,and rate of airflow over the nozzle.

FIG. 3 illustrates a modified form of nozzle, generally referenced A,and which has many parts in common with the nozzle of FIG. 1. Whereapplicable the same reference numerals have been applied to these parts.

In the nozzle 10A, a major constructional difference is that the bossdirectly connects the nosepiece M and tailpiece 16 to one anotherwithout the interposition of a centerpiece equivalent to the centerpiece18. The spray orifice 38 is again formed between faces 39 and 40 which,in this construction, are on the tail and nose pieces 16 and 14respectively. The width of the orifice 38 is controlled by rotating thetailpiece 16 with respect to the boss 20 so that the fine threading onthe tail portion 36 of the boss 20 and on the tailpiece 16 causesrelative axial movement between the pieces 14 and 16.

The other major constructional difference between the emhodiment of FIG.1 and the embodiment of FIG. 3 is that the nonretum valve is arrangedsomewhat differently. The seat 28 is formed not on the boss 20 but on acylindrical component 54 which is rigidly secured by means of a pin or agrub screw 56 to the boss 20. The seat 28, has, however, the samerounded configuration as the seat 28 of the embodiment of FIG. 1. Thevalve does not include a diaphragm (equivalent to the diaphragm 30) butinstead the disc 32 is pressed directly against the seat 28 by thespring 34. The valve functions to permit flow of spray liquid to theorifice 38 but to prevent flow of gas or liquid in the reverse directiontherethrough.

The inlet connection 24 leads to the hollow interior of the component 54so that the inlet connection 24 is placed in direct communication withone face of the disc 32.

Another slight difference between the construction of FIG. 3 and theconstruction of FIG. 1 is that the spring 42, instead of bearing on theend of the bore in the tailpiece l6, bears against a washer 60 locatedin the bore.

A transverse bore 62 is provided in the boss 20. This bore 62 has nofunction during use of the nozzle but is provided so that it can receivea tommy bar or the like during assembly of the nozzle. This greatlyfacilitates the act of screwing the boss 20 into the nosepiece 14.

The operation of the nozzle 10A is substantially identical to theoperation of the nozzle 10, the disc 32 being displaced from the seat 28when fluid under pressure is supplied to the inlet connection 24 therebypermitting the spray liquid to flow through the radial holes 46 to thecavity 45 and thence to the spray orifice 38.

The nozzles indicated in the drawings are particularly suitable for usein aerial spraying. It will, of course, be understood that forvariations in rates of airflow, wide variations in construction and3rzroportions willbe permissible.

The faces and 40, defining the spray orifice 38, are forwardly inclinedin order to counter the Coanda effect between the spray fluid and thefaces 39 and 40, and the adjacent surfaces of pieces 18 and 16(FlG. 1)or 14 and 16 (FIG. 3) in close proximity to the orifice 38.

When used for aerial spraying, the airflow across the nozzle is, ofcourse, produced by the forward motion of the aircraft. When the nozzleis used in an application wherein it is stationary, the airflow isinduced so that the flow of air into the concave side of the dishedcurtain occurs in the desired manner. Thus an airflow is induced if thenozzle is used in paint spraying, in a cooling tower or as a liquid fuelatomizer for a gas turbine engine.

We claim:

1.. A nozzle comprising an elongated body of a streamlined form having afront end and a rear end, an inlet for feeding spray liquid to theinterior of the nozzle, and a circumferential spray orifice positionedintermediate said ends and defined between two facing surfaces of thebody, each of said surfaces being generally frustoconical in form withthe outer periphery of each surface closer to said front end than itsinner periphery, and said inlet being forward of said orifice.

2. A nozzle as claimed in claim 1, wherein said surfaces divergeslightly towards said front end.

3. A noule according to claim 2, wherein the angle between each of saidfaces and the axis along which the body is elongated is approximately60.

4. A method of spraying which comprises feeding spray liquid to theinterior of a nozzle having an elongated body of streamlined form, thebody having a front end and rear end, feeding the spray liquid from theinterior of the nozzle to the exterior thereof through a circumferentialspray orifice defined between two frustoconical surfaces of the body,the frustoconical surfaces being positioned so that the emerging sprayliquid is in the form of a generally conical curtain which divergestowards said front end, the included angle between said curtain and theline along which the body is elongated being approximately 60, andshattering the curtain of spray liquid by means of an airstream flowingover the nozzle.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 :857D d November 9 1971 Inventor(s) Johannes Hendrik RAUTENBACH and MaitlandREED It is certified that error appears in the above-identified patentand that said Letters Patent are hereby corrected as shown below:

In column 1, line 8, the name of the assignee should read:

Aviation Design 6; Engineering Company South Africa (Proprietary)Limited.

Signed and sealed this 18th day of April 1972.

(SEAL) AttG-Sti EDWARD M.FLETCHLBR,JR.

ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents USCOMM-DCGOSTG-PGQ \LS GOVERNMENY PHINYING OFFICE 1 9| D-358-33l

1. A nozzle comprising an elongated body of a streamlined form having afront end and a rear end, an inlet for feeding spray liquid to theinterior of the nozzle, and a circumferential spray orifice positionedintermediate said ends and defined between two facing surfaces of thebody, each of said surfaces being generally frustoconical in form withthe outer periphery of each surface closer to said front end than itsinner periphery, and said inlet being forward of said orifice.
 2. Anozzle as claimed in claim 1, wherein said surfaces diverge slightlytowards said front end.
 3. A nozzle according to claim 2, wherein theangle between each of said faces and the axis along which the body iselongated is approximately 60*.
 4. A method of spraying which comprisesfeeding spray liquid to the interior of a nozzle having an elongatedbody of streamlined form, the body having a front end and rear end,feeding the spray liquid from the interior of the nozzle to the exteriorthereof through a circumferential spray orifice defineD between twofrustoconical surfaces of the body, the frustoconical surfaces beingpositioned so that the emerging spray liquid is in the form of agenerally conical curtain which diverges towards said front end, theincluded angle between said curtain and the line along which the body iselongated being approximately 60*, and shattering the curtain of sprayliquid by means of an airstream flowing over the nozzle.